test-rawmemchr: make more robust * modules/rawmemchr-tests (Files): Add zerosize-ptr.h, mmap-anon.m4. (Depends-on, configure.ac): Add needed prerequisites to use it. * modules/memchr-tests (Files, Depends-on, configure.ac): Likewise, to avoid implicit reliance on memchr module prereqs. * tests/test-memchr.c (main): Ensure proper masking. * tests/test-rawmemchr.c (main): Likewise. Detect oversized reads. Signed-off-by: Eric Blake <eblake@redhat.com>

Files:
tests/test-rawmemchr.c
tests/zerosize-ptr.h
tests/signature.h
tests/macros.h
m4/mmap-anon.m4

Depends-on:
extensions
getpagesize

configure.ac:
dnl Check for prerequisites for memory fence checks.
gl_FUNC_MMAP_ANON
AC_CHECK_HEADERS_ONCE([sys/mman.h])
AC_CHECK_FUNCS_ONCE([mprotect])

Makefile.am:
TESTS += test-rawmemchr
check_PROGRAMS += test-rawmemchr